This paper discusses the very general question of how syntactic features of individual languages relate to the universal set of syntactic features. It is pointed out that Chomsky’s approach (2001a) to this fundamental issue is paradoxical. On one hand he argues that language is uniform in the relevant sense (L-uniformity), but, on the other hand, he also assumes that languages make different selections of features from a universal feature set (L-selection). The paper argues strongly that L-uniformity is the only conceivable possibility. However, if that is correct, a great deal of what languages have is common is ‘silence’, that is, categories that are present in Narrow Syntax but silent in PF. In other words, language has innate elements and structures irrespective of whether or how they are overtly expressed. It follows that language variation is to a substantial extent ‘silence variation’, that is, much of it boils down to languages being explicit vs. silent about different (syntactically active) categories. This claim is coined as the Silence Principle, saying that any meaningful feature of language may be silent.